ansi-styles 6.2.3: bgColor

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify ansi-styles.bgColor in pkg:npm/ansi-styles@6.2.3
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/ansi-styles@6.2.3
Demonstrate these symbols/APIs:
  - ansi-styles.bgColor
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:22e5b45764d8255b36c5aacd51e0ca8d80c94171bb2e67e2c9b7a53356d25768","constraints":{"executionContext":"node"},"contract":["ansiStyles.bgColor provides standard and bright background colors with matching open and close ANSI escape sequences","ansiStyles.bgColor.close defines the default background reset escape sequence","ansiStyles.bgColor.ansi converts standard ANSI color codes to background escape sequences","ansiStyles.bgColor.ansi256 generates 256-color palette background ANSI escape codes","ansiStyles.bgColor.ansi16m converts RGB values into 24-bit truecolor background ANSI escape codes","applyBackgroundColor applies background color styling including standard names, 256-color palette, and truecolor RGB to text"],"goal":"verify ansi-styles.bgColor in pkg:npm/ansi-styles@6.2.3","kind":"HOW","packages":["pkg:npm/ansi-styles@6.2.3"],"schemaVersion":1,"symbols":["ansi-styles.bgColor"]},"contractCommand":["node","test/contract.js"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","language":"javascript","libc":"glibc","libcVersion":"2.39","moduleSystem":"cjs","os":"linux","osVersionBucket":"24","packageManager":"npm","packageManagerVersion":"10.9.8","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/ansi-styles@6.2.3"],"schemaVersion":1,"subject":"pkg:npm/ansi-styles@6.2.3","symbols":["ansi-styles.bgColor"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-ansi-styles-bg-color",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-ansi-styles-bg-color",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "ansi-styles": "6.2.3"
      }
    },
    "node_modules/ansi-styles": {
      "version": "6.2.3",
      "resolved": "https://registry.npmjs.org/ansi-styles/-/ansi-styles-6.2.3.tgz",
      "integrity": "sha512-4Dj6M28JB+oAH8kFkTLUo+a2jwOFkuqb3yucU0CANcRRUbxS0cP0nZYCGjcc3BNXwRIsUVmDGgzawme7zvJHvg==",
      "license": "MIT",
      "engines": {
        "node": ">=12"
      },
      "funding": {
        "url": "https://github.com/chalk/ansi-styles?sponsor=1"
      }
    }
  }
}

{
  "name": "sample-ansi-styles-bg-color",
  "version": "1.0.0",
  "private": true,
  "description": "Clean-room verification for ansi-styles bgColor",
  "main": "src/index.js",
  "scripts": {
    "test": "node test/contract.js"
  },
  "dependencies": {
    "ansi-styles": "6.2.3"
  },
  "license": "MIT-0"
}

{
  "schemaVersion": 1,
  "goal": "verify ansi-styles.bgColor in pkg:npm/ansi-styles@6.2.3",
  "kind": "HOW",
  "packages": [
    "pkg:npm/ansi-styles@6.2.3"
  ],
  "symbols": [
    "ansi-styles.bgColor"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

const ansiStylesModule = require('ansi-styles');

const ansiStyles = ansiStylesModule.default || ansiStylesModule;
const { bgColor } = ansiStyles;

/**
 * Returns the bgColor object from ansi-styles.
 * @returns {object}
 */
function getBgColor() {
  return bgColor;
}

/**
 * Retrieves standard or bright background color style pair.
 * @param {string} name
 * @returns {{ open: string, close: string }}
 */
function getNamedBgColor(name) {
  const style = bgColor[name];
  if (!style) {
    throw new Error(`Unknown background color: ${name}`);
  }
  return {
    open: style.open,
    close: style.close,
  };
}

/**
 * Formats a background color escape sequence using a 256-color palette index.
 * @param {number} code
 * @returns {{ open: string, close: string }}
 */
function getAnsi256BgColor(code) {
  if (typeof code !== 'number' || code < 0 || code > 255) {
    throw new RangeError(`Color code must be between 0 and 255: ${code}`);
  }
  return {
    open: bgColor.ansi256(code),
    close: bgColor.close,
  };
}

/**
 * Formats a background color escape sequence using 24-bit truecolor RGB values.
 * @param {number} red
 * @param {number} green
 * @param {number} blue
 * @returns {{ open: string, close: string }}
 */
function getAnsi16mBgColor(red, green, blue) {
  return {
    open: bgColor.ansi16m(red, green, blue),
    close: bgColor.close,
  };
}

/**
 * Applies background styling to the provided text.
 * @param {string} text
 * @param {{ name?: string, ansi256?: number, rgb?: [number, number, number] }} options
 * @returns {string}
 */
function applyBackgroundColor(text, options = {}) {
  let openSequence = '';
  const closeSequence = bgColor.close;

  if (options.name) {
    openSequence = getNamedBgColor(options.name).open;
  } else if (typeof options.ansi256 === 'number') {
    openSequence = getAnsi256BgColor(options.ansi256).open;
  } else if (Array.isArray(options.rgb) && options.rgb.length === 3) {
    const [r, g, b] = options.rgb;
    openSequence = getAnsi16mBgColor(r, g, b).open;
  } else {
    throw new Error('Must specify one of name, ansi256, or rgb options');
  }

  return `${openSequence}${text}${closeSequence}`;
}

module.exports = {
  ansiStyles,
  bgColor,
  getBgColor,
  getNamedBgColor,
  getAnsi256BgColor,
  getAnsi16mBgColor,
  applyBackgroundColor,
};

const assert = require('node:assert');
const {
  ansiStyles,
  bgColor,
  getBgColor,
  getNamedBgColor,
  getAnsi256BgColor,
  getAnsi16mBgColor,
  applyBackgroundColor,
} = require('../src/index.js');

// 1. ansiStyles.bgColor provides standard and bright background colors with matching open and close ANSI escape sequences
assert(bgColor && typeof bgColor === 'object', 'bgColor must be an object');
assert.strictEqual(getBgColor(), bgColor);

const standardBgColors = {
  bgBlack: '\u001B[40m',
  bgRed: '\u001B[41m',
  bgGreen: '\u001B[42m',
  bgYellow: '\u001B[43m',
  bgBlue: '\u001B[44m',
  bgMagenta: '\u001B[45m',
  bgCyan: '\u001B[46m',
  bgWhite: '\u001B[47m',
};

for (const [name, expectedOpen] of Object.entries(standardBgColors)) {
  const style = bgColor[name];
  assert(style, `Missing standard style ${name}`);
  assert.strictEqual(style.open, expectedOpen, `${name} open code mismatch`);
  assert.strictEqual(style.close, '\u001B[49m', `${name} close code mismatch`);

  const named = getNamedBgColor(name);
  assert.strictEqual(named.open, expectedOpen);
  assert.strictEqual(named.close, '\u001B[49m');
}

const brightBgColors = {
  bgBlackBright: '\u001B[100m',
  bgRedBright: '\u001B[101m',
  bgGreenBright: '\u001B[102m',
  bgYellowBright: '\u001B[103m',
  bgBlueBright: '\u001B[104m',
  bgMagentaBright: '\u001B[105m',
  bgCyanBright: '\u001B[106m',
  bgWhiteBright: '\u001B[107m',
};

for (const [name, expectedOpen] of Object.entries(brightBgColors)) {
  const style = bgColor[name];
  assert(style, `Missing bright style ${name}`);
  assert.strictEqual(style.open, expectedOpen, `${name} open code mismatch`);
  assert.strictEqual(style.close, '\u001B[49m', `${name} close code mismatch`);
}

// Aliases
assert.deepStrictEqual(bgColor.bgGray, bgColor.bgBlackBright);
assert.deepStrictEqual(bgColor.bgGrey, bgColor.bgBlackBright);

// 2. ansiStyles.bgColor.close defines the default background reset escape sequence
assert.strictEqual(bgColor.close, '\u001B[49m');

// 3. ansiStyles.bgColor.ansi converts standard ANSI color codes to background escape sequences
assert(typeof bgColor.ansi === 'function', 'bgColor.ansi must be a function');
assert.strictEqual(bgColor.ansi(30), '\u001B[40m');
assert.strictEqual(bgColor.ansi(31), '\u001B[41m');
assert.strictEqual(bgColor.ansi(32), '\u001B[42m');
assert.strictEqual(bgColor.ansi(37), '\u001B[47m');

// 4. ansiStyles.bgColor.ansi256 generates 256-color palette background ANSI escape codes
assert(typeof bgColor.ansi256 === 'function', 'bgColor.ansi256 must be a function');
assert.strictEqual(bgColor.ansi256(0), '\u001B[48;5;0m');
assert.strictEqual(bgColor.ansi256(100), '\u001B[48;5;100m');
assert.strictEqual(bgColor.ansi256(255), '\u001B[48;5;255m');

const bg256 = getAnsi256BgColor(200);
assert.strictEqual(bg256.open, '\u001B[48;5;200m');
assert.strictEqual(bg256.close, '\u001B[49m');

assert.throws(() => getAnsi256BgColor(-1), RangeError);
assert.throws(() => getAnsi256BgColor(256), RangeError);

// 5. ansiStyles.bgColor.ansi16m converts RGB values into 24-bit truecolor background ANSI escape codes
assert(typeof bgColor.ansi16m === 'function', 'bgColor.ansi16m must be a function');
assert.strictEqual(bgColor.ansi16m(255, 128, 0), '\u001B[48;2;255;128;0m');
assert.strictEqual(bgColor.ansi16m(0, 0, 0), '\u001B[48;2;0;0;0m');
assert.strictEqual(bgColor.ansi16m(12, 34, 56), '\u001B[48;2;12;34;56m');

const bg16m = getAnsi16mBgColor(10, 20, 30);
assert.strictEqual(bg16m.open, '\u001B[48;2;10;20;30m');
assert.strictEqual(bg16m.close, '\u001B[49m');

// 6. applyBackgroundColor applies background color styling including standard names, 256-color palette, and truecolor RGB to text
const message = 'Sample Text';
assert.strictEqual(applyBackgroundColor(message, { name: 'bgCyan' }), `\u001B[46m${message}\u001B[49m`);
assert.strictEqual(applyBackgroundColor(message, { name: 'bgRedBright' }), `\u001B[101m${message}\u001B[49m`);
assert.strictEqual(applyBackgroundColor(message, { ansi256: 45 }), `\u001B[48;5;45m${message}\u001B[49m`);
assert.strictEqual(applyBackgroundColor(message, { rgb: [255, 100, 50] }), `\u001B[48;2;255;100;50m${message}\u001B[49m`);

assert.throws(() => applyBackgroundColor(message, { name: 'invalidBg' }), /Unknown background color: invalidBg/);
assert.throws(() => applyBackgroundColor(message, {}), /Must specify one of name, ansi256, or rgb options/);

console.log('All contract assertions passed successfully.');